Lianyungang Institute of Agricultural Sciences in Jiangsu Xuhuai Region, Jiangsu Academy of Agricultural Sciences, Lianyungang 222000, China.
National Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Int J Mol Sci. 2019 Mar 23;20(6):1474. doi: 10.3390/ijms20061474.
Cadmium (Cd) has the potential to be chronically toxic to humans through contaminated crop products. MicroRNAs (miRNAs) can move systemically in plants. To investigate the roles of long-distance moving xylem miRNAs in regulating maize response to Cd stress, three xylem sap small RNA (sRNA) libraries were constructed for high-throughput sequencing to identify potential mobile miRNAs in Cd-stressed maize seedlings and their putative targets in maize transcriptomes. In total, about 199 miRNAs (20⁻22 nucleotides) were identified in xylem sap from maize seedlings, including 97 newly discovered miRNAs and 102 known miRNAs. Among them, 10 miRNAs showed differential expression in xylem sap after 1 h of Cd treatment. Two miRNAs target prediction tools, psRNAtarget (reporting the inhibition pattern of cleavage) and DPMIND (discovering Plant MiRNA-Target Interaction with degradome evidence), were used in combination to identify, via bioinformatics, the targets of 199 significantly expressed miRNAs in maize xylem sap. The integrative results of these two bioinformatic tools suggested that 27 xylem sap miRNAs inhibit 34 genes through cleavage with degradome evidence. Moreover, nearly 300 other genes were also the potential miRNAs cleavable targets without available degradome data support, and the majority of them were enriched in abiotic stress response, cell signaling, transcription regulation, as well as metal handling. These approaches and results not only enhanced our understanding of the Cd-responsive long-distance transported miRNAs from the view of xylem sap, but also provided novel insights for predicting the molecular genetic mechanisms mediated by miRNAs.
镉 (Cd) 可通过受污染的作物产品对人类造成慢性毒性。 microRNAs (miRNAs) 可在植物体内系统性移动。为了研究长距离移动的木质部 miRNAs 在调节玉米对 Cd 胁迫的反应中的作用，构建了三个木质部汁液小 RNA (sRNA) 文库进行高通量测序，以鉴定 Cd 胁迫玉米幼苗中潜在的可移动 miRNAs 及其在玉米转录组中的推定靶标。总共在玉米幼苗木质部汁液中鉴定出约 199 个 miRNA（20-22 个核苷酸），包括 97 个新发现的 miRNA 和 102 个已知的 miRNA。其中，10 个 miRNA 在 Cd 处理 1 小时后在木质部汁液中差异表达。两个 miRNA 靶标预测工具 psRNAtarget（报告切割的抑制模式）和 DPMIND（发现具有降解组证据的植物 miRNA-靶标相互作用）被结合使用，通过生物信息学方法鉴定玉米木质部汁液中 199 个显著表达的 miRNA 的靶标。这两个生物信息学工具的综合结果表明，27 个木质部汁液 miRNA 通过降解组证据抑制 34 个基因。此外，近 300 个其他基因也是潜在的 miRNA 可切割靶标，没有可用的降解组数据支持，其中大多数基因富集在非生物胁迫反应、细胞信号转导、转录调控以及金属处理中。这些方法和结果不仅增强了我们从木质部汁液角度对 Cd 响应的长距离运输 miRNAs 的理解，而且为预测 miRNA 介导的分子遗传机制提供了新的见解。
